Turn bar system for web processing machine



Sept. 14, 1965 w, F. HUCK 3,206,089

TURN BAR SYSTEM FOR WEB PROCESSING MACHINE Filed July 24, 1963 FIG. m M F 5 Sheets-Sheet l f/ FIG. 2 1: 11

I NVENTOR.

A/IZA/AM F. 6 064 Sept. 14, 1965 w. F. HUCK 3, 6

TURN BAR SYSTEM FOR WEB PROCESSING MACHINE Filed July 24, 1963 3 Sheets-Sheet 2 INVENTOR. 20b E 4444 4 19067? ms /al$ Sept. 14, 1965 w. F. HUCK 3, 06

TURN BAR SYSTEM FOR WEB PROCESSING MACHINE Filed July 24, 1963 5 Sheets-Sheet 3 INVENTOR. /\//LA 64/! A #0671 United States Patent 3,205,089 TURN BAR SYSTEM FOR VEB PROCESSING lYIA'CHLNE William F. Huck, 81 Greenway Terrace, Forest Hills, N.Y. Filed July 24, 1963, Ser. No. 297,360 11 Claims. (Cl. 226- 40) This invention relates to a system or apparatus for controlling the position and travel of and preventing damage to webs of flexible material, such as bands, ribbons, strips, strands or other continuous planiform bodies of paper, cloth, felt, metal or plastic foil, or the like, as the webs are passed over angularly disposed web turning bars, herein referred to as turn bars, by which the direction of their movement or their orientation is changed.

More particularly, the invention is concerned with turn bar systems for rotary web processing machines in which the web is likely to be subjected to tension levels of high or variable magnitude as it is turned in direction or inverted while being drawn to a rotary processing unit from a preceding rotary unit of the machine. The preceding unit may be a printing unit, a roll stand delivering a preprinted web from a roll thereof, a web or ribbon collator, or some other unit which propels a web or an assembly of webs and from which the web or web assembly is drawn continuously to be processed by a further rotary propelling unit, such as a rotary printing unit, a perforator, a folder, a collating or binding apparatus, or the like, after having been turned or inverted by the turn bar system.

It is well recognized that the turn bars in machines of the character mentioned give rise to web breaks and register difiiculties and limit the speeds with which the machines can be operated satisfactorily. Although the turn bars often are provided in the form of perforated tubes through which compressed air is passed to maintain a thin cushion of air between the web and the bars, or in the form of freely rotating rollers supported by anti-friction bearings, these expedients for reducing the frictional drag of the bars on the Web still leave serious problems of sidelay variation, web misalignment and web breakage in the turning of webs on machines operated at increasingly high web speeds or upon webs of great width. The reduction of drag at the bars does not overcome the difficulties which arise from the relatively high tension levels of the web leads to and from the bars and from the variations of web length and web tension which occur with variations of the speed, width, thickness, strength, moisture content, temperature or other conditions of the Web material.

It has been proposed to deal with such problems by providing, in advance of and following the turn bars, web forwarding rollers rotated continuously at a speed higher than the web speed, or driven through slip clutches so r0- tated, so as to impart a forward pull or drag to the web and thus to reduce the friction between the web and the bars. An arrangement of that nature, however, depends upon intricate relationships of relative speeds and frictional forces and varies in its action with variations of web conditions so that it is not capable of overcoming the difficulties above mentioned.

It is therefore a principal object of the present invention to provide a web turning system or apparatus by which such difiiculties can be effectively overcome.

Another object is to provide a web turning system or apparatus which will effectively control the position and travel of the web passing over the turn bars and avoid damage to the Web at the bars notwithstanding variations of the speed, thickness, width strength, moisture content, temperature or other conditions of the moving Web material.

3,206,089 Patented Sept. 14, 1965 A further object of the invention is to provi e Such a system or apparatus which is readily adaptable to the processing of webs of difierent materials or of different sizes.

According to this invention the turn bar or bars disposed angularly relative to the web path in a machine of the character mentioned are associated with control means which act to maintain substantially constant predetermined tensions, without dependence upon the web speed or other variable web conditions, in respective sections of the web running to and from the bar or bars, and each of these control means, or at least one of them under less exacting operating conditions, is provided in the form of a mechanism that non-slippably engages the web and propels it in a tension controlled synchronism with the speed of said units while setting and holding substantially constant the tension in the web approaching the mechanism.

In this way, the tension levels in the web leads to and from the turn bar or bars can be set and held at a desired magnitude without limitation by the web speed or by the tension levels or variations of conditions occurring elsewhere in the machine, and the web can be kept travelling steadily over each turn bar at a tension best suited to the turning operation, with little or no attendant problems of side-lay variations, web damage, or misregister.

Other objects, features and advantages of the invention and preferred ways of practicing it will be apparent from the following description and the accompanying schematic drawings of illustrated embodiments of the invention. In the drawings:

FIG. 1 is a diagrammatic illustration of a multi-unit rotary web processing machine having a turn bar system to invert the web passing between two printing units;

FIG. 2 is a diagrammatic plan view of an arrangement of turn bars and associated control mechanisms suitable for inverting the web;

FIG. 3 is a diagrammatic plan view of another arrangement thereof, whereby a web processed on one side by a unit of one press line is inverted and directed into an adjacent press line to be processed on the other side;

FIG. 4 is a schematic side elevation, partly in section, of a web inverting system suitable for the arrangement of FIGS. 1, 2 or 3;

FIG. 5 shows similarly a modification of the system of FIG 4, in which a web-propelling tension control mechanism act upon the web loop between the turn bars, at the so-called bay window;

FIGS. 6 and 7 are views corresponding respectively to FIGS. 4 and 5 but of systems embodying a modified form of the tension control mechanism; and

FlG. 8 is a schematic side elevation of a further modification of the invention.

In the arrangement diagrammed in FIG. 1, a web W propelled from a roll stand or other rotary unit of the machine is passed through a first printing unit U which imprints the web on one side and propels it onward through the machine for delivery to a second printing unit U acting upon the reverse side of the web. In the course of its travel to the second printing unit, to which the web 1s drawn by the propelling action of rotary elements of that unit, the web is passed through a turn bar system which includes tension control mechanisms TC; and TC acting upon the web leads passing to and from a set of web inverting turn bars TB; and T3 Before reaching the turn bar system, the Web ordinarily will travel over an extended series of web guides each of which imposes a drag increasing the web tension; and for high speed printing work of high quality the ink applied to the web by the first printing unit U ordinarily will be dried by passing the web through an oven or other heating system, and then over cooling rollers, before it is inverted. Such heating and cooling operations have pronounced and widely variable effects upon the dimensions and tension of the web and the stability of its travel over the turn bars.

The turn bar system according to FIG. 1 consists of conventional turn bars TB and TB disposed crosswise at opposite angles of 45 to the web path, with a bay window roller or rollers guiding a Web loop L between the bars and with the tension control mechanisms TC and TC acting respectively upon the web leads passing to and from the turn bars. As seen in FIG. 2, the web from the first of these mechanisms passes beneath, around and from the upper side of the first turn bar TB into the loop L, which is disposed to one side of the normal web path on a guide roller or rollers BWR; and the return leg of the loop passes over and around the second turn bar T3 leaving the lower side of that bar under the action of the second control mechanism TC Another effective arrangement of a web inverting turn bar system according to the invention is shown schematically in FIG. 3. Here, two web processing machines, such as two printing presses P and P disposed side by side, may be used effectively as a single machine to print or otherwise process one side of the web W in one press and then the other side of the web in the second press. After the printing and other actions on the web in the first press, the web W is passed through the first control mechanism TC and then to and around the first turn bar TB these elements being part of the first press. From the first turn bar the web travels into a loop L on a guiding roller BWR at the far side of the second press P and then back to the second turn bar T13 and around it to and through the second control mechanism TC The latter elements are part of and are aligned with the printing unit of the second press.

The control mechanisms TC and TC; in either of the illustrated arrangements are advantageously of the type shown in FIG. 4 or FIG. 6. The carriage type shown in FIG. 4 is preferable for use with relatively wide webs, while the fixed roller type shown in FIG. 6 is preferred for use with relatively narrow webs.

Referring more particularly to FIG. 4, the two control mechanisms there shown are designated A and A respectively. The first of these includes a web propelling roller or rollers, for example, a driven roller 10 coacting with spring-pressed pressure rollers 11, which are mounted for horizontal floating movement with a roller supporting carriage 12. The web lead to the turn bars approaches these rollers in a section W extending horizontally from a fixed idler roller 8 to driven roller 10, and it leaves them in a vertically extending section W running to one or more idler rollers, such as roller 9, and from the latter to the lower side of the first turn bar TB The carriage 12 has sleeve bearings 13 by which itis slidable on horizontal rods 14 supported in fixed position on the machine frame (not shown) The web propelling roller 10 is rotatably mounted between side plates of the carriage and has a driven pulley 15 secured to one of its journals. The pulley 15 is a V-belt pulley driven by a V-belt 16 which extends to it from a driving V-belt pulley 17 secured to a drive shaft 18. That shaft, in turn, is driven from the main drive shaft of the web processing machine through non-slip connections, including a nonslippable or turning belt 19, whereby the speed of shaft 18 and pulley 17 is always synchronized to that of the web processing units U and U The driving V-belt pulley 17 is a pulley of variable pitch diameter, the halves of which are constantly biased toward each other by a spring or the equivalent so as to urge the belt toward its maximum driving diameter and thus increase the raito of the speed of pulley 15 and roller 10 to the speed of the driving pulley 17 and that of the web processing units of the machine. Variable diameter V-belt pulleys suitable for this purpose are well known, a preferred construction being disclosed in US. Patent No. 2,812,666 issued November 12, 1957.

The V-belt 16 is deflected out of a straight path and thus pre-tensioned by one or more idler rollers, two of which are illustrated at 2% and 21 in FIG. 4. These rollers keep the V-belt under tension produced by the spring or equivalent means constantly urging the variable di* ameter pulley 15 to its maximum driving diameter. It will be evident, however, that the extent of displacement of the belt by the idler roller or rollers, hence the tension of the V-belt, the pitch diameter of pulley 15 and the speed ratio of the V-belt drive, depends upon the location of the carriage 12 and will be varied by a displacement of the carriage along the supporting rods 14.

The tension of the web section W approaching the carriage rollers 14 11 tends constantly to displace the carriage to the left as viewed in FIG. 4. The carriage position is not materially affected by the tension in the vertically extending web section W running from these rollers to roller 9 and the turn bars; nor is the length of that section materially afiected by a change of the carriage position.

On the other hand, the carriage is constantly urged in the right-hand direction against the tension of web section W by the pre-set force of yieldable biasing means such, for example, as a tension spring 22 connected with the carriage through a lever 23 and a link 24. The force of the biasing means may be adjusted to any desired value by suitable means such, for example, as an adjustably positioned screw 25 anchoring one end of spring 22. A dashpot 26 connected with an arm of lever 23 serves to dampen movements of the carriage so that there will be little or no tendency for the mechanism to hunt in reaching an equilibrium position.

Accordingly, the tension of the web section W being drawn to the web propelling carriage rollers 10, 11 continuously urges the carriage 12 in one direction, while the force of the biasing spring 22 and the reaction of the V- belt 16 to its pressure against the rollers 20, 21 urge the carriage continuously in the opposite direction, i.e., to the right as seen in FIG. 4. When the sum of that force and that reaction is in baance with the tension of web section W the carriage stands still, the web propelling speed of its rollers is constant, and the tension of the web section is at a magnitude determined by the pre-set force of the spring 22.

This web tension, moreover, is kept at substantially the same magnitude, notwithstanding variations of the conditions affecting the web in its travel to the turn bar system, by the action of the control mechanism.

When a variation of tension begins to develop in the web lead approaching rollers 10, 11, the carriage moves incrementally to restore the balance of forces, and the tension of V-belt 16 is thus varied correspondingly so as to vary proportionately the speed of these rollers and thereby restore the tension in that web lead to the pre-set value determined by the force of the spring. At the same time, since the web is positively propelled by roller 10 asv it is moved through section W to enter the turn bars, the tension and other conditions of its travel over the turn bars are kept independent of the conditions affecting the web before it reaches the turn bar system and are governed, instead, by the coaction of the second control mechanism A with the other elements of the system.

The second control mechanism A is quite similar to mechanism A differing from the latter mainly in that it is oppositely oriented and has its carriage-mounted driven V-belt pulley 15a formed as the variable diameter pulley, instead of the driving V-belt pulley 17a. Parts of the mechanism A substantially corresponding to parts described above in connection with mechanism A are designated by corresponding reference numerals suffixed with the letter a.

The web section W leaving the second turn bar TB runs horizontally to the web propelling rollers 10a, 11a of mechanism A from which the web passes in a vertical run to suitable web guides leading it to the second processing unit U of the machine.

The force of the spring 22a urging the carriage 12a to the right is counterbalanced by the tension of web section W and by the reaction of the V-belt 16a to its pressure against the rollers 29a and 21a. The carriage 12a and its rollers a, 11a thus have an equilibrium position in which the web is propelled at a speed synchronized to the speed of the processing units, with the tension in the web section W at a magnitude determined by the pre-set force of spring 220.

The mechanism acts continuously, in substantially the same manner as mechanism A to maintain this tension substantially constant. When the pull of web section W on roller 10a tends to increase, the carriage 12a and its rollers move incrementally to the left, thus proportionately reducing the tension of V-belt 16a and causing the driven pulley a to increase proportionately in diameter and thus to be reduced proportionately in speed until the tension in the web section leaving the turn bars is again in balance with the pre-set forces opposing it.

Conversely, when the pull of web section W on the carriage roller tends to decrease, the spring 2.2a incrementally displaces the carriage to the right, thus proportionately increasing the tension of V-belt 16a, reducing the pitch diameter and increasing the speed of driven pulley 15a, and bringing the web tension and opposing forces back into balance.

Accordingly, the control mechanism A sets and holds substantially constant the magnitude of the tension in the web leaving the turn bars; doing so, by virtue of the coaction of mechansm A without dependence upon the conditions affecting the web before it reaches the turn bar system; and since the drag eiects of the turn bars and the bay window roller acting upon the web are ordinarily substantially constant under the conditions maintained by the two control mechanisms, the respective tensions in the web sections running to and between the turn bars will ordinarily be kept substantially constant at values which can be easily set so as to assure the required stable and reliable travel of the web over the turn bars.

A modification of the system above described is advantageous for uses where the cumulative drag of the two turn bars and the bay window roller on the web would raise the tension level of the web on or leaving the turn bars beyond a limiting value suitable for the material being processed. For the avoidance of difficulties in such cases, a roller or set of rollers guiding the web loop at the bay window of the system may be made to serve as web propelling driven roller means of a tension control mechanism of the type already described, as illustrated schematically at A in FIG. 5.

The mechanism A is quite similar to mechanism A Parts of it corresponding substantially to parts seen in FIG. 4 are designated by corresponding reference numerals sufiixed with the letter 1).

The web section W leaving the first turn bar T13 runs horizontally to web propelling rollers 10b, 10c, 11b of mechanism A from which the web passes vertically downward over a fixed guide roller 27 and from the latter over another fixed guide roller 28 into web section W running to the lower side of the second turn bar T3 The driven rollers 10!; and 180, as shown, have the web trained over them in a serpentine manner. They are mounted on a carriage 12b for floating movement along rods 14!) in the manner previously described, and are driven by a variable diameter V-belt pulley 15b mounted on a journal of roller 1%.

The variable diameter pulley 15b is connected through V-belt 1617 with driving pulley 1712, which has a fixed diameter and is driven synchronously with the web processing units of the machine. The V-belt is tensioned by rollers b and 21]), its reaction to their pressure tending to move the carriage to the right in the direction of the pull of web section W The carriage is biased continuously in the opposite direction by a constant pre-set force applied to it through link 24b and lever 2312 from a fluid pressure cylinder 22b. A pressure fluid, such as compressed air, is supplied continuously to the cylinder 22b under a constant pressure selected so as to bias the carriage against the tension of web section W with a force corresponding to the tension value desired to be maintained in that web section.

The mechanism A acts in substantially the same manner as the mechanisms previously described. When the pull of web section W on roller 10b tends to increase, the carriage 12b and its rollers move incrementally to the right, thus proportionately reducing the tension of V-belt 16b and causing the driven pulley 15b to increase proportionately in diameter and thus to be reduced proportionately in speed until, through the incremental reduction of the relative speed of propelling roller 1%, the tension in the Web section entering the bay window loop is again in balance with the pre-set force opposing it. Conversely, when the pull of web section W on the carriage roller tends to decrease, the fluid pressure in cylinder 22b incrementally displaces the carriage to the left, thus proportionately increasing the tension of V-belt 16b, reducing the pitch diameter and increasing the speed of driven pulley 15b, and bringing the web tension and opposing forces back into balance.

Accordingly, the control mechanism A sets and holds substantially constant the magnitude of the tension in the web entering the loop between the turn bars and, correspondingly, in the web entering the turn bars from mechanism A doing so without dependence upon the conditions affecting the web before it reaches the turn bar system and without varying the distance traveled by the web section W running to the second turn bar TB in the return leg of the loop. The tension and position of that web section then are controlled and held substantially constant by the action of mechanism A on web section W leaving the turn bars; and the tension maintained by this mechanism can be set at a level much lower than would be practicable if web section W were subject to the cumulative drag of the two turn bars and a roller or rollers at the bay window.

The embodiments of the invention illustrated in FIGS. 6 and 7 correspond in arrangement and functions to those of FIGS. 4 and 5, respectively, difiering from the latter essentially only in that the tension control mechanisms employed are of a fixed roller type as above mentioned, instead of the described carriage type.

According to FIG. 6, mechanisms B and B having fixed web propelling means act respectively upon the web leads to and from the web inverting turn bars TB and T13 which again are illustrated as elements of a system such as diagrammed in FIGS. 1-3. According to FIG. 7, a mechanism substantially identical to mechanism B of FIG. 6 acts upon the loop of the web passing between the turn bars.

It should sufiice to describe particulars of the first of these mechanisms, as shown at B in FIG. 6, and to designate corresponding parts of mechanisms B and B by corresponding reference numerals sufiixed with the letters a and b respectively. The dilferences of orientation and web travel involved will be evident from the drawings, and it is to be noted that, again, in each control mechanism drawing the web from a turn bar the V-belt pulley, rather than the driving V-belt pulley, is the pulley of variable pitch diameter.

The Web W moving to the turn bar system from parts of the machine following the first printing unit U passes over a fixed idler roller 30 into a loop M of the web, which is maintained by a floating roller 31 carried at the end of a lever arm 32. From this roller the web passes to a fixed web propelling roller 33, which is driven by a V-belt pulley 34 secured to one of its journals. Spring biased pressure rollers 35 hold the web positively in nonslipping engagement with the propelling roller 33. From the latter the Web passes over a guide roller 36 into a run passing horizontally to the lower side of the first run bar TB The driven V-belt pulley 34 is connected by V-belt 37 with a driving V-belt pulley 38 of variable pitch diameter, the latter being driven continuously in synchronism with the web processing units as previously described. The V-belt is deflected out of a straight path between its two pulleys by a roller 39 carried on an arm 41 which is positioned and moves with floating roller arm 32 on a supporting axis at 41. Movements of the lever system thus constituted are dampened by springs 42 and dashpot 43 connected with arm 44 of the same system.

A tension spring 45 anchored adjustably by screw 46 constantly pulls on the arm 32 with a force opposing the force exerted upon the floating roller 31 by a web loop M, which latter force always corresponds to the tension of the web approaching the turn bar system.

Accordingly, the tension of the web approaching the system is maintained at a substantially constant value determined by the force of spring 45. When this web tension tends to increase, the floating roller 31 is displaced incrementally to the right against the tension of the spring 45, and roller 39 correspondingly increases the tension of V-belt 37 and causes a proportionate decrease of the pitch diameter of the driving pulley 38 and of the speed of the driven pulley 34. The opposite actions occur when the tension of the approaching web tends to decrease. Therefore, the web is always drawn to the propelling roller 33 under a substantially constant predetermined tension and propelled from this roller so as to enter the turn bars under the controlled conditions established by the coaction of the control mechanism B or, according to FIG. 7, of that mechanism B with the other elements of the system.

A further modification of the invention as shown in FIG. 8 may he used in machines operating under conditions which do not subject the web lead to the turn bars.

to very high or very widely varying tensions. According to this modification, the web section W leaving the turn bars is controlled by a web propelling control mechanism of one of two types hereinabove described, this mechanism, as shown, being of the form seen at A in FIG. 4; and the web lead to the turn bars is controlled by a simple floating roller control mechanism C of well known construction and operation. The web W approaching mechanism C from the first printing unit moves over a guide roller into a loop N positioned by a floating roller 52 which is constantly balanced against the pull of the web loop by suitable biasing means, such as a fluid pressure cylinder 53, acting with a constant force upon the supporting arm 54 of the floating roller. From the loop N the web is suitably guided to the first turn bar as by idler rollers 55 and 56.

The constantly biased floating roller 52 establishes and holds a definite, selectable value of tension in the web section entering the turn bars, provided that the web approaching it need not be so tight or subject to such wide variations of conditions that the range of effectiveness of such a simple floating roller device would be exceeded. By virtue of the action of roller 52 and the simultaneous action of mechanism A the respective tensions in the web section passing between and leaving the turn bars are kept at substantially constant, though increased, levels up to the point of the propulsion of web section W by the driven roller of control mechanism A That roller then supplies the energy required to propel the web steadily to, over and away from the turn bars while enabling the web to be drawn onward to the second processing unit U under conditions favorable to the operation of that unit.

It will be understood that the invention herein set forth may be embodied in various arrangements and forms of apparatus other than those particularly described hereinabove and illustrated in the drawings and that the invention is not restricted to the illustrative embodiments except as may be required by a fair construction of the appended claims.

What is claimed is:

1. In a web processing machine including a rotary web propelling processing unit to which a web is drawn from a preceding rotary propelling unit of the machine and bar means disposed angularly to the web path for turning the web passing between said units:

first control means including a floating roller yieldably biased against the web lead to said bar means for maintaining a substantially constant tension level in at least the section of said lead approaching said control means,

and second control means including driven roller means non-slippably engaging and propelling the web lead from said bar means, means for driving said roller means in synchronism with but at a speed variable transiently relative to the speed of said units, and means responsive to the tension of the web section leaving said bar means for regulating the speed ratio of said driving means so as to keep said tension substantially constant,

whereby the web on the bar means is kept under substantially constant force irrespective of tension variations occurring in sections of the web between said units and said control means.

2. In a web processing machine including a rotary web propelling processing unit to which a web is drawn from a preceding rotary propelling unit of the machine and bar means disposed angularly to the web path for turning the web passing between said units:

first control means including driven roller means nonslippably engaging and propelling the web lead to said bar means, means for driving said roller means in synchronism with but at a speed variable transiently relative to the speed of said units, and means responsive to the tension of the web section approaching said roller means for regulating the speed ratio of said driving means so as to keep said tension substantially constant,

and second control means including second driven roller means non-slippably engaging and propelling the Web lead from said bar means, second means for driving said second roller means in synchronism with but at a speed variable transiently relative to the speed of said units, and second means responsive to the tension of the Web section leaving said bar means for regulating the speed ratio of said second driving means so as to keep the tension of said leaving Web section substantially constant,

whereby the web on the bar means is kept under substantially constant force of a magnitude determined by said control means irrespective of tension variatrons occurring in sections of the web between said units and said control means.

3. A web processing machine according to claim 2, said driven roller means including a displaceable web propelling roller mounted for floating movement along the path of said approaching web section, said reguating means including yieldable means acting with a predetermined control force to urge said roller in a direction opposite to the direction in which it is urged by the tension of said approaching web section, and said driving means lncluding a variable speed belt drive the speed ratio of which is varied upon and in proportion to displacements of said roller.

4. A web processing machine according to claim 2, said driven roller means including a web propelling roller mounted in fiXed position, said driving means including a variable speed belt drive the speed ratio of which is varied upon and in proportion to variations of a control force applied to the driving belt thereof, and said regulating means including a floating roller engaging and urged in one direction by the tension of said approaching Web section, yieldable means acting with a predetermined force to urge said floating roller in the opposite direction and means positioned by said floating roller for applying said control force to said belt.

5. A Web processing machine according to claim 2, said second driven roller means including a displaceable web propelling roller mounted for floating movement along the path of said leaving web section, said second regulating means including yieldable means acting with a predetermined control force to urge said roller in a direction opposite to the direction in which it is urged by the tension of said leaving web section, and said second driving means including a variable speed belt drive the speed ratio of which is varied upon and in proportion to displacements of said roller.

6. A web processing machine according to claim 2, said second driven roller means including a web propelling roller mounted in fixed position, said second driving means including a variable speed belt drive the speed ration of which is varied upon and in proportion to variations of a control force applied to the driving belt thereof, and said second regulating means including a floating roller engaging and urged in one direction by the tension of said leaving web section, yieldable means acting with a predetermined force to urge said floating roller in the opposite direction and means positioned by said floating roller for applying said control force to said belt.

7. In a web processing machine including a rotary web propelling processing unit to which a web is drawn from a preceding rotary propelling unit of the machine, turn bars respectively disposed at opposite angles to the web path for inverting the web passing between said units, and roller means guiding a loop of the web passing between the turn bars:

first control means including a floating roller yieldably biased against the web lead to said bars for maintaining a substantially constant tension level in at least the section of said lead approaching said first control means,

second control means including driven roller means non-slippably engaging and propelling the web lead from said bars, means for driving said roller means in synchronism with but at a speed variable transiently relative to the speed of said units, and means responsive to the tension of the web section leaving said bars for regulating the speed ratio of said driving means so as to keep said tension substantially constant,

and third control means including means holding said loop non-slippably in driven relation to said guiding roller means, third means for driving said guiding roller means in synchronism with but at a speed variable transiently relative to the speed of said units, and third means responsive to the tension of the Web section entering said loop for regulating the speed ratio of said third driving means so as to keep the tension of said entering web section substantially constant,

whereby the web on the turn bars is kept under substantially constant forces irrespective of tension variations occurring in sections of the web between said units and said control means.

8. A web processing machine according to claim 7, said guiding roller means including a displaceable web propelling roller mounted for floating movement along the path of said entering web section, said third regulating means including yieldable means acting with a predetermined control force to urge said displaceable roller in a direction opposite to the direction in which it is urged by the tension of said entering web section, and said third driving means including a variable speed belt drive the speed ratio of which is varied upon and in proportion to displacements of said displaceable roller.

9. A web processing machine according to claim 7, said guiding roller means including a web propelling roller mounted in fixed position, said third driving means including a variable speed belt drive the speed ratio of which is varied upon and in proportion to variations of a control force applied to the driving belt thereof, and said third regulating means including a floating roller engaging and urged in one direction by the tension of said entering Web section, yieldable means acting with a predetermined force to urge said floating roller in the opposite direction and means positioned by said floating roller for applying said control force to said belt.

10. In a web processing machine including a rotary web propelling processing unit to which a web is drawn from a preceding rotary propelling unit of the machine, turn bars respectively disposed at opposite angles to the web path for inverting the web passing between said units, and roller means guiding a loop of the web passing between the turn bars:

first control means including driven roller means nonslippably engaging and propelling the web lead to said bars, means for driving said roller means in synchronism with but at a speed variable transiently relative to the speed of said units, and means responsive to the tension of the web section approaching said roller means for regulating the speed ratio of said driving means so as to keep said tension substantially constant, second control means including second driven roller means non-slippably engaging and propelling the Web lead from said bars, second means for driving said second roller means in synchronism with but at a speed variable transiently relative tothe speed of said units, and second means responsive to the tension of the web section leaving said bars for regulating the speed ratio of said second driving means so as to keep the tension of said leaving Web section substantially constant, and third control means including means holding said loop non-slippably in driven relation to said guiding roller means, third means for driving said guiding roller means in synchronism with but at a speed variable transiently relative to the speed of said units, and third means responsive to the tension of the web section entering said loop for regulating the speed ratio of said third driving means so as to keep the tension of said entering web section substantially constant,

whereby the web on the turn bars is kept under substantially constant forces of magnitudes determined by said control means irrespective of tension variations occurring in sections of the web between said units and said control means.

11. In a web processing machine including a rotary web propelling processing unit to which a web is drawn from a preceding rotary propelling unit of the machine, tum bars respectively disposed at opposite angles to the web path for inverting the web passing between said units, and roller means guiding a loop of the web passing between the turn bars:

control means including means holding said loop nonslippably in driven relation to said guiding roller means, means for driving said guiding roller means in synchronism with but at a speed variable transiently relative to the speed of said units, and means responsive to the tension of the web section entering said loop for regulating the speed ratio of said driving means so as to keep the tension of said entering web section substantially constant, and

second control means including second driven roller means non-slippably engaging and propelling the web lead from said bars, second means for driving said second roller means in synchronism with but at a speed variable transiently relative to the speed of said 1 1 12 units, and second means responsive to the tension of 7 References Cited by the Examiner the Web section leaving said bars for regulating the UNITED STATES PATENTS speed ratio of said second driving means so as to keep the tension of said leaving web section substantially 300,162 6/84 Taylor 226 197 3,083,887 4/63 Huck 226-41 constant, 5

whereby the Web on the turn bars is kept under substantially constant forces irrespective of tension varia- ROBERT REEVES Prlmary Exammer tions occurring in sections of the Web between said RAPHAEL M. LUPO, Examiner.

units and said control means. 

1. IN A WEB PROCESSING MACHINE INCLUDING A ROTARY WEB PROPELLING PROCESSING UNIT TO WHICH A WEB IS DRAWN FROM A PRECEDING ROTARY PROPELLING UNIT OF THE MACHINE AND BAR MEANS DISPOSED ANGULARLY TO THE WEB PATH FOR TURNING THE WEB PASSING BETWEEN SAID UNITS: FIRST CONTROL MEANS INCLUDING A FLOATING ROLLER YIELDABLE BIASED AGAINST THE WEB LEAD TO SAID BAR MEANS FOR MAINTAINING A SUBSTANTIALLY CONSTANT TENSION LEVEL IN AT LEAST THE SECTION OF SAID LEAD APPROACHING SAID CONTROL MEANS, AND SECOND CONTROL MEANS INCLUDING DRIVEN ROLLER MEANS NON-SLIPPABLY ENGAGING AND PROPELLING THE WEB LEAD FROM SAID BAR MEANS, MEANS FOR DRIVING SAID ROLLER MEANS IN SYNCHRONISM WITH BUT AT A SPEED VARIABLE TRANSIENTLY RELATIVE TO THE SPEED OF SAID UNITS, AND MEANS RESPONSIVE TO THE TENSION OF THE WEB SECTION LEAVING SAID BAR MEANS FOR REGULATING THE SPEED RATIO OF SAID DRIVING MEANS SO AS TO KEEP SAID TENTION SUBSTANTIALLY CONSTANT, WHEREBY THE WEB ON THE BAR MEANS IS KEPT UNDER SUBSTANTIALLY CONSTANT FORCE IRRESPECTIVE OF TENSION VARIATIONS OCCURRING IN SECTIONS OF THE WEB BETWEEN SAID UNITS AND SAID CONTROL MEANS. 